Drop2DV-pal wont convert .vob file

[Gothboy]

Hi,

I am trying to convert a .vob file to .dv with Drop2DV but get the following error message:

Input #0, mpeg, from '/Volumes/JOHN_MEDIA/Psycho_rip/PSYCHO/TITLE01-ANGLE1.VOB':
Duration: 00:04:28.3, start: 113.286367, bitrate: 5291 kb/s
Stream #0.0: Video: mpeg2video, 720x576, 25.00 fps
Stream #0.1: Audio: ac3, 48000 Hz, mono, 96 kb/s
Output #0, dv, to '/Volumes/JOHN_MEDIA/Psycho_rip/PSYCHO/TITLE01-ANGLE1.VOB.dv':
Stream #0.0: Video: dvvideo, 720x576, 25.00 fps, q=2-31, 200 kb/s
Stream #0.1: Audio: pcm_s16le, 48000 Hz, mono, 768 kb/s
Stream mapping:
Stream #0.0 -> #0.0
Stream #0.1 -> #0.1
[dv @ 0x39c4b0]Can't initialize DV format!
Make sure that you supply exactly two streams:
video: 25fps or 29.97fps, audio: 2ch/48Khz/PCM
Could not write header for output file #0 (incorrect codec parameters ?)

Can anyone help